Indonesia's palm oil business is not only fueling the world’s worst fires, it’s enabling a murderous trade in trafficking of animals, including orangutans.

Young primates increasingly are growing up as orphans, their mothers killed by poachers, wildlife experts such as Panut Hadisiswoyo say.

In northern Sumatra's Gunung Leuser National Park, refugees of rapacious deforestation are reintroduced into a semi-wild existence. Once-captive mother orangutans are raising their children in the hills of the Leuser ecosystem, Asia's most biodiverse forest.

Panut Hadisiswoyo, founder of the Orangutan Information Center, leads patrols against illegal poaching. He says the trade thrives because deforestation hems the animals into shrinking enclaves and makes them easier to hunt down.

Increasing demand for exotic pets in southeast Asia heightens the orangutans' vulnerability, Hadisiswoyo said. "To get the baby [orangutan], they must shoot the mother. ... Traders want to sell orangutans to overseas, including to Malaysia, to Thailand."

The poachers operate largely in the 2.6 million-hectare Leuser ecosystem, home to some 6,700 orangutans as well as rhinos, elephants, tigers and leopards.

In Sumatra, more than 1.3 million hectares of habitat, much inside Leuser, was lost to deforestation from 2001 to 2014, according to Global Forest Watch.

Perhaps the biggest culprit is illegal plantations of palm oil, a boom crop used in most snacks and cosmetics.

Peatland is drained and cleared by burning, destroying habitats and sparking the world’s worst fires.

People like Ian Singleton, founder of the Sumatran Orangutan Conservation Program, are left to deal with victims.

"When these companies go into these areas, they’ll chop all the major trees down. They’ll bulldoze it, they’ll burn it and they’ll kill every living thing, even down to ants and mosses and lichens. ... Most of the orangutans are killed in that process, too," said Singleton. "I always refer to these as the lucky survivors of that apocalyptic wave of destruction, but they’re also refugees."

The semi-autonomous government in Aceh province now wants to open up vast tracts of Leuser – almost half, according to conservation groups – for legal cultivation.

Those working to protect the animals say that would be an abject disaster.